It is known in the prior art to apply puncture sealants made of puncture sealing rubber or plastic material on the crown portion of the tire so that when a sharp object such as a nail pierces the tire, the tire sealant forms a seal around the puncture. Tire sealants of this nature tend to flow or be soft resulting in a tendency to migrate towards the center portion of the tire due to centrifugal force as the tire is rotated at high speeds. Thus the outer portions of the crown have reduced sealant volume due to migration of the sealant towards the center. It is known in the prior art to compartmentalize a sealant into multiple cells such as shown in U.S. Pat. No. 2,877,819 or U.S. Pat. No. 4,388,261. One disadvantage to compartmentalizing the sealant into multiple cells is that the manufacturing process is costly. Further, having too many compartments may impede the effective flow of the sealant needed to seal a puncture. Further, it was conventional wisdom that using an extruder to manufacture the sealant into compartments is costly and requires additional manufacturing steps.
In US patent publication 2009/0159182 A1 published Jun. 25, 2009 Robert Lammlein Jr. proposed an apparatus employing conveyor and strip applying devices to assemble three or more sealant strips in an assembly having sealant material in strips with non-sealant dividers separating the strip of sealant. This publication, “Method and Apparatus For Building A Puncture Sealant Preassembled Component” was believed to be a simple way to assemble the sealant into a partitioned strip of sealant as a preassembled component. Once built, the assembly could be delivered to a tire building machine to be used in the manufacture of a self-sealing tire. Mr. Lammlein's invention achieved a partitioned sealant layer by the use of an apparatus employing conveyors and strip appliers to attach divider strips between adjacent sealant strips.
Similarly in JP 2006-14925, slits were cut into a sealant strip and non-sealant rubber dividers were placed in the slits to achieve a similar result.
In JP 2003-334868 an upper or lower non-sealant layer with a plurality of projecting walls was used to form partitions as circumferential ribs to divide the sealant into hoop like annular rings about the tire or alternatively will transverse and circumferential partition walls to form numerous cells of sealant material. A rather large and not easily overcome difficulty in this sealant strip assembly was removal of entrapped air. As every tire builder can easily appreciate having pockets of air in an uncured green tire can cause large problems during high temperature curing. Great care is taken to avoid entrapped air and therefore most tire builders would want to avoid any assembly that promotes the occurrence of entrapped air.
In all the prior art attempts to use sealants in tires it has been a goal to minimize the amount of sealant material used to keep tire weight increases to a minimum. This is important as the added weight tend to increase tire heat build-up during driving and tends to increase the vehicle's fuel consumption. Accordingly, engineers have been working hard to provide a self-sealing tire resistant to punctures, but without decreasing the tire uniformity or performance.
A second objective is to provide this self-sealing feature at a very low additional cost. For the most part of a tire's useful life, flats are not that common an occurrence, but when they occur, it is almost always at a most inconvenient time for the driver. Many vehicles have air pressure sensors mounted in the wheels to alert the driver to seek assistance and repair. Some vehicles are equipped with self-supporting runflat tires with reinforced sidewalls, but these are rather costly. The sealant tire is a good reliable lower cost solution that won't sustain tire pressure on large openings, but will certainly keep a tire from losing air pressure from a nail or screw puncture. These punctures are generally the most common cause of flat tires and for the typical vehicle a sealant or self-sealing tire is the best insurance against tire punctures because it is believed the most affordable solution.
The present invention as described as follows provides what is believed to be a most cost efficient approach to manufacturing a compartmentalized sealant strip assembly.